Mono-n-fattycitramides



MONO-N-FATTYCITRAMIDES Kendrick R. Eiiar, Minneapolis, Minn, assignor to General Mills, Inc., a corporation of Delaware No Drawing. Application June 20, 1952, Serial No. 294,730

6'Claims. (Cl. 260-534) The present invention relates to mono-N-fattycitral5 mides and their salts as represented by the formula:

CHzOONRrRz HOOGOOM HzCOOM CHzCOOH CHiCONRiRZ RiRzNH HOC-COOH HOC-COOH H20 CHzCOOH CHzCOOH CHZCONIMR CHzCONRrRz HO -COOH ZMOH HO-C-COOM 1120 OOH HnCOOM The reaction proceeds through the intermediate step of the fatty ammonium citrate salt which then dehydrates to form the amide. In preparing the amide the fatty 4 amine and the citric acid are mixed in equimolar quantities and heated until there is no longer any fatty ammonium ion present in the mixture. This condition can be determined by simply titrating a sample of the reaction mixture with perchloric acid reagent (0.1 N perchloric acid in acetic acid). Where a secondary fatty amine is employed in the reaction, the product obtained at this point is the pure monoamide. Where primary amines are employed, however, the monoamide may dehydrate to form the imide so that the reaction mixture will contain monoamide and imide, usually in the ratio of about 1 to 2. The imide, however, can easily be hydrolyzed to the monoamide by heating with alkali. This results in the production of the disodium salt of the monoamide. In producing the disodium salt of the monoamide, the stoichiometric quantity of alkali, as an aqueous solution, is added to the crude product, and the mixture is heated. The quantity of alkali required may be calculated from the ratio of amide to imide which in turn may be determined by titration of a sample in alcohol with alkali to the phenolphthalein end point. The disodium salt may be used directly as a concentrated aqueous solution, or the salt may be isolated as a pure dry solid by precipitation with a water miscible organic solvent, such as alcohol, followed by filtration and drying. The ammonium salt may be obtained in place of the sodium salt by the employment of ammonium hydroxide for the hydrolysis of the imide. The free acid compound may be prepared from the sodium salt or by fractionation of the mixture of amide and imide. The secondary amines react more slowly and, accordingly, a higher temperature and a longer reaction time is preferred. The citric acid may be employed in the form of the anhydrous acid or of the hydrated crystalline acid.

In the reaction with primary amines, temperatures in the range of -175 C. may be employed. With sec- 2,693,490 Patented Nov. 2,1954

orsigary amines the reaction may be carried out at 2 C.

The fatty amines which may be employed in the present invention include both primary and secondary fatty amines in which the fatty groups each contain from 8-22 carbon atoms. These fatty amines are customarily produced from fatty acids through the medium of the nitrile which is subsequently reduced to the amine. In the preparation of the amines, the mixed fatty acids of a fat or oil or any selected fraction thereof, or any isolated single fatty acid may be used. These fatty acids, and consequently the amines, may be either saturated or unsaturated. Because of their superior wetting properties, the amines having fatty groups containing from 10-14 carbon atoms are preferred.

EXAMPLE 1 Dodecylamine (37 g.) and citric acid monohydrate (42 g.) were heated together in an open flask with gentle stirring. The mixture soon became almost solid as the salt was formed. As the temperature approached 100 C. the mixture softened and began to foam due to the elimination of water; the foam was kept stirred down. As the temperature rose above 100 C. the mixture slowly melted to a tan liquid. Heating and stirring were continued and aliquots were withdrawn from time to time and titrated with perchloric acid in acetic acid solution. When titration showed no alkylammonium ion in the mixture it was cooled. The change of amine number with time and temperature, starting from the softening point, is illustrated 1n the table.

Table Elapsed Time, min. 9 5 i-g Titration of the product dissolved in alcohol with aqueous sodium hydroxide showed it to have a neutral equivalent of 277. Since the theoretical neutral equivalents of the monoamide and imide are 180 and 341, respectively, the product is approximately 66% imide and 34% amide.

The product (25 g.) was added to 150 ml. of Water containing the calculated quantity, 5.76 g., of sodium hydroxide. The solution was refluxed until it became homogeneous and clear. Its pH was then 9.2. The pure disodium salt was obtained by evaporating the solution to dryness and drying the residue over P205. (Calcd for CmHarOsNNaz; C, 53.59; H, 7.75; N, 3.47; found: C, 53.14; H, 7.53; N, 3.65.)

The product had good surface-active properties: a 0.30% solution gave 138 mm. of foam in the Ross-Miles test and a wetting time of 86 sec. in the canvas disc test.

The free acid form of the product was prepared by acidifying an aqueous solution of the disodium salt. The precipitated mono-N-dodecyl-citramide was then filtered, washed with water, and dried. It was a waxy solid, soluble in organic solvents but insoluble in water.

EXAMPLE 2 The equivalent quantity of tetradecylamine was substituted for dodecylamine in the procedure of Example 1. The product, disodium mono N- tetradecylcitramidate, showed excellent surface-active properties; a 0.25% solution gave 180 mm. of exceptionally stable foam in the Ross-Miles test and a wetting time of 15.1 sec. in the canvas disc test.

EXAMPLE 3 The equivalent quantity of octadecylamine was substituted for dodecylamine in the procedure of Example 1. The product, disodium mono-N-octadecylcitramidate, gave a clear aqueous solution at 0.25% concentration. It showed good surface-active properties, particularly at elevated temperatures (140 mm. of foam at 25 C.; mm. at 50 C.).

3 EXAMPLE 4 Dioctylamine (24.1 g.) and citric acid monohydrate (21.0 g.) were heated together for 14 hours at 135-160. Titration of the product with perchloric acid showed that it still contained some unreacted amine. The latter and any unreacted acid were removed by dissolving the product in chloroform and extracting with dilute hydrochloric acid. Evaporation of the extracted chloroform solution gave mono-N,N-dioctyl-citramide as a waxy brown solid. An aqueous solution of its sodium salt was prepared by dissolving 4.2 g. of the material in 25 ml. of water containing 0.8 g. of sodium hydroxide. The solution exhibited moderate wetting and foaming properties.

I claim as my invention:

1. Compounds having the following formula:

in which R1 is an aliphatic hydrocarbon group containing from 8-22 carbon atoms, R2 is selected from the group consisting of hydrogen and R1, and M is selected from the group consisting of ammonium and alkali metal.

2. Compounds having the following formula:

OHzCONHR HO--CCOOM CHzOOOM 4 in which R is an aliphatic hydrocarbon group containing from 8-22 carbon atoms, and M is selected from the group consisting of ammonium and alkali metal.

3. Compounds having the following formula:

GHaCONHR -COONa CHaCOONa in which R is an aliphatic hydrocarbon group containing from 8-22 carbon atoms.

4. Disodium mono-N-dodecylcitramidate.

5. Disodium mono-N-tetradecylcitramidate.

6. Disodium mono-N-octadecylcitrarnidate.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Christ Jan. 3, 1950 OTHER REFERENCES Number Outline of Org. Nitrogen Compounds, p. 

1. COMPOUNDS HAVING THE FOLLOWING FORMULA: 